Semiconductor device comprising an N-type transistor with an N-type semiconductor containing nitrogen as a gate
A semiconductor device such as a transistor with an excellent OFF characteristic even when a channel is short is provided. A periphery of a source is surrounded by an extension region and a halo region, a periphery of a drain is surrounded by an extension region and a halo region, and a substrate with low impurity concentration is not in contact with the source or the drain. Moreover, a high-work-function electrode is provided via a gate insulator, and electrons entering the vicinity of a surface of the substrate from the extension regions are eliminated. With such a structure, the impurity concentration of the channel region can be decreased even when the channel is short, and a favorable transistor characteristic can be obtained.
1. A semiconductor device comprising:
a channel region;
a gate insulator over the channel region, and
an n-type semiconductor provided on and in contact with the gate insulator,
wherein a concentration of donors and acceptors in the channel region is less than 1×10 −3 nm −3 ,
wherein a channel length of the semiconductor device is 100 nm or less,
wherein the n-type semiconductor contains oxygen, nitrogen and one selected from the group consisting of indium, tin, and zinc,
wherein the contained oxygen is 2 to 5 times of the contained nitrogen,
wherein the n-type semiconductor comprises crystals having a wurtzite-type crystal structure,
wherein the n-type semiconductor has a work function of 5.5 eV or more, and
wherein a relation of N d 1/2 ×t ox ×L<1 [nm 1/2 ] is satisfied where N d [nm −3 ] is the concentration of donors and acceptors in the channel region, t ox [nm] is a thickness of the gate insulator when it is assumed as silicon oxide, and L [nm] is the channel length.
2. The semiconductor device according to claim 1 , wherein the channel region comprises silicon.
3. The semiconductor device according to claim 1 , further comprising an extension region and a halo region,
wherein the extension region is provided in contact with the channel region and the halo region.
4. A semiconductor device comprising an n-type transistor, the n-type transistor comprising:
a channel region;
a gate insulator over the channel region;
two extension regions provided in contact with the channel region;
a source;
a drain;
two halo regions; and
an n-type semiconductor provided on and in contact with the gate insulator,
wherein the n-type semiconductor contains oxygen, nitrogen and one selected from the group consisting of indium, tin, and zinc,
wherein the contained oxygen is 2 to 5 times of the contained nitrogen,
wherein the n-type semiconductor comprises crystals having a wurtzite-type crystal structure,
wherein the n-type semiconductor has a work function of 5.5 eV or more,
wherein one of the halo regions is provided in contact with one of the extension regions and one of the source and the drain,
wherein the channel region contains an n-type shallow impurity region provided in contact with the gate insulator and both of the two extension regions,
wherein the channel region contains a low-concentration impurity region having a p-type conductivity provided in contact with the n-type shallow impurity region and both of the two extension regions, and
wherein the n-type transistor shows normally-off characteristics.
5. The semiconductor device according to claim 4 , wherein the channel region comprises silicon.
6. The semiconductor device according to claim 4 , wherein the carrier concentration of the n-type semiconductor is 1×10 20 cm −3 or more.
7. The semiconductor device according to claim 4 , wherein a distance between the extension regions is 100 nm or less.
8. The semiconductor device according to claim 4 , wherein the n-type shallow impurity region is shallower than each of the extension regions.
9. A semiconductor device comprising an n-type transistor, the n-type transistor comprising:
a single crystal semiconductor region;
a gate insulator over the single crystal semiconductor region;
two extension regions provided in contact with the single crystal semiconductor region;
a source;
a drain;
two halo regions; and
an n-type semiconductor provided on and in contact with the gate insulator,
wherein a distance between the two extension regions is 100 nm or less,
wherein the n-type semiconductor contains oxygen, nitrogen and one selected from the group consisting of indium, tin, and zinc,
wherein the contained oxygen is 2 to 5 times of the contained nitrogen,
wherein the n-type semiconductor comprises crystals having a wurtzite-type crystal structure,
wherein the n-type semiconductor has a work function of 5.5 eV or more,
wherein each of the two halo regions is provided in contact with one of the two extension regions and one of the source and the drain,
wherein a concentration of impurities of the single crystal semiconductor region is 1×10 15 cm ˜ 3 or less, and
wherein each of the source and the drain is not in contact with the single crystal semiconductor region.
10. The semiconductor device according to claim 9 , wherein the single crystal semiconductor region comprises a single crystal silicon.
11. The semiconductor device according to claim 9 , wherein the carrier concentration of the n-type semiconductor is 1×10 20 cm −3 or more.
12. The semiconductor device according to claim 9 , wherein each of the source and the drain is entirely surrounded by one of the two halo regions and by one of the two extension regions.
13. A semiconductor device comprising:
a single crystal semiconductor region;
a gate insulator over the single crystal semiconductor region, and
an n-type semiconductor provided on and in contact with the gate insulator,
wherein a concentration of donors and acceptors in the single crystal semiconductor region is less than 1×10 −3 nm −3 ,
wherein a channel length of the semiconductor device is 100 nm or less,
wherein the n-type semiconductor contains oxygen, nitrogen and one selected from the group consisting of indium, tin, and zinc,
wherein the contained oxygen is 2 to 5 times of the contained nitrogen,
wherein the n-type semiconductor comprises crystals having a wurtzite-type crystal structure,
wherein the n-type semiconductor has a work function of 5.5 eV or more, and
wherein a relation of N d 1/2 ×t ox ×L<1 [nm 1/2 ] is satisfied where N d [nm −3 ] is the concentration of donors and acceptors in the single crystal semiconductor region, t ox [nm] is a thickness of the gate insulator when it is assumed as silicon oxide, and L [nm] is the channel length.
14. The semiconductor device according to claim 13 , wherein the single crystal semiconductor region comprises a single crystal silicon.
15. The semiconductor device according to claim 13 , further comprising an extension region and a halo region,
wherein the extension region is provided in contact with the single crystal semiconductor region and the halo region.